In this paper, risk acceptability evaluation and risk weight and improved risk level were added in original risk matrix method according to its shortcomings and practicality and need of evaluation of investment risk in international engineering project. A model based on improved risk matrix method was put forward to evaluate investment risk in international engineering project. Firstly, investment risk evaluation index system of international engineering project was established. Secondly, level of risk factors were decided by risk impact level and risk probability scope, borda ordinal value was calculated to form judgment matrix, analytic hierarchy process was introduced to calculate risk weight. Synthetic risk level was determined by product of quantized value of risk level and corresponding risk weight. Risk acceptability evaluation was decided by risk impact level and risk probability scope. Finally, a case study was presented to verify the feasibility of the model which would provide a reliable basis for the investment decision.